System for characterizing a passive antenna network and elements in a distributed antenna system

ABSTRACT

A distributed antenna system includes a plurality of remote antenna units with a passive element coupled to at least one of the remote antenna units at a connection juncture. An RFID system is associated with the first passive element and has RFID data identifying the first passive element. An interrogator unit is associated with the remote antenna unit and is configured for generating a least one signal for transmission to the passive element to be reflected at the connection juncture and received at the interrogator unit. The interrogator unit is also configured for generating at least one signal for transmission to the RFID system to obtain the RFID data identifying the passive element. Processing circuitry processes the reflected signal and measures a parameter of the first passive element. The processing circuitry correlates the measured parameter with the RFID data for the passive element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/211,148, filed on Jul. 15, 2016, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/193,401, filed on Jul. 16,2015, all of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the invention are directed to wireless communicationsystems, and specifically directed to a distributed antenna system forwireless communications.

BACKGROUND OF THE INVENTION

Distributed antenna systems (DAS) can be used in confined areas todeploy wireless coverage and capacity to mobile devices. A DAS caninclude active elements such as master units, extension units, andremote units. Among the variety of active elements, a typical DAS mayinclude passive elements as well. Examples of such passive elements are:coaxial cables, RF splitters, RF combiners, RF antennas, optical fiber,optical splitters, optical combiners, attenuators, dummy loads, cablefeeds, and surge protectors. Other passive RF or optical devices caninclude connectors, jacks, wall jacks, and patch cords.

Systems are presented for detecting the presence of passive RF orpassive optical devices that are present in a DAS. The presence of suchdevice can be facilitated through the employment of radio frequencyidentification (RFID) chips. One aspect includes coupling the RFID chipto the device that is to be detected. In one aspect of such systems, acoupling network is used to couple to a signal wave inside of awaveguide such as coaxial cable, optical fiber or other type ofwaveguide. Examples of the coupling network are resonant couplingnetworks, bandpass filters, low pass filters, high pass filters, anddirectional or non-directional couplers. One purpose of the couplingnetwork is to pass a maximum of RF energy coming from the interrogatoror RFID reader to the RFID chip. Another feature of such systems is thatthey block other signals used in the DAS at different frequencies thanthe RF interrogator frequency to avoid potential generation ofintermodulation products by the potential non-linear characteristic ofthe RFID chip.

In such systems, a DAS is provided that includes one or more passiveelements. Each passive element can be associated with an RFID chip. TheRFID chip may be integrated into the passive element or may be coupled,connected, or otherwise associated with the passive element. A readermay be integrated within or otherwise associated with a sub-system ofthe DAS that is remote from at least some of the passive elements. Thereader can transceive RFID signals over a communications network of theDAS. The communications network may include, for example, coaxial cableor another transmission medium that can carry RF signals and RFIDsignals through the DAS. For example, the reader may transmit an RFIDsignal that is carried by the communications network through a couplingnetwork to the RFID chip associated with a passive element.

The RFID chip can respond to the RFID signal with a responsive signalrepresenting an identifier of the passive element. The responsive signalcan be received from the coupling network and transported by thecommunications network to the reader. The reader may extract theidentifier from the responsive signal and provide the identifier to acontroller. The passive element may not be required to be powered for areader to detect the presence of the passive element. Both the readerand the RFID chip may be configured to be in a fixed position within theDAS, as opposed to the reader being moveable. In other aspects, thereader includes one or more readers that are moveable.

An RFID chip may be any item that can respond to an RFID signal with aresponsive signal representing an identifier for the item. An “RFIDchip” may also be known as an “RFID tag.”

One such system is described in U.S. patent application Ser. No.13/798,517, filed Mar. 13, 2013 and entitled “Detecting Passive RFComponents Using Radio Frequency Identification Tags”, which applicationis incorporated herein by reference in its entirety.

To fully characterize a passive network beyond the active boundaries ofa distributed antenna system, additional information is necessary,beyond determining the presence and identification of passive RFdevices. The location, physical distance and layout and insertion lossof such elements is desired. Therefore, there is a need for such a DASsystem that, in addition to determining the presence and identificationof various passive elements in a DAS, can further provide othercharacteristics and parameters for passive elements in the DAS.

SUMMARY

One embodiment is directed to a distributed antenna system comprising aplurality of remote antenna units. A first passive element is coupled toat least one of the remote antenna units at a connection juncture. Thedistributed antenna system further comprises an RFID system associatedwith the first passive element and having RFID data identifying thefirst passive element and an interrogator unit associated with theremote antenna unit. The interrogator unit is configured for generatinga least one signal for transmission to the passive element to bereflected at the connection juncture and received at the interrogatorunit. The interrogator unit is configured for generating at least onesignal for transmission to the RFID system to obtain the RFID dataidentifying the passive element. The distributed antenna system furthercomprises processing circuitry for processing the reflected signal andfor measuring a parameter of the first passive element, the processingcircuitry further configured for correlating the measured parameter withthe RFID data for the passive element.

Another embodiment is directed to a method of characterizing a firstpassive element of a distributed antenna system that comprises aplurality of remote antenna units. The first passive element is coupledto at least one of the remote antenna units at a connection juncture.The method comprises generating, by an interrogator unit associated withthe remote antenna unit, at least one signal for transmission to thepassive element to be reflected at the connection juncture and receivedat the interrogator unit. The method further comprises generating, bythe interrogator unit, at least one signal for transmission to an RFIDsystem associated with the first passive element, to obtain RFID dataidentifying the first passive element. The method further comprisesprocessing the reflected signal and measuring a parameter of the firstpassive element and correlating the measured parameter with the RFIDdata for the passive element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a distributed antenna system forimplementing the present invention.

FIG. 2 is a block diagram of passive elements of a distributed antennasystem consistent with an embodiment of the invention.

FIG. 3 is a block diagram of passive elements of a distributed antennasystem consistent with another embodiment of the invention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of embodimentsof the invention. The specific design features of the system and/orsequence of operations as disclosed herein, including, for example,specific dimensions, orientations, locations, and shapes of variousillustrated components, will be determined in part by the particularintended application and use environment. Certain features of theillustrated embodiments may have been enlarged, distorted or otherwiserendered differently relative to others to facilitate visualization andclear understanding.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a system incorporating RFID technology todetermine the network presence, location and layout of the passivedevices. The passive RF elements of the inventive system incorporateRFID systems (chips) that are closely coupled to the otherwise passiveRF elements or RF input or output. Time Domain Reflectometry (TDR) isused in combination with the RFID systems in order to identify passivenetwork elements and locate them in the network structure. The RFIDsystem receives an interrogator signal or a sequence of interrogatorsignals and uses the energy to prepare a response. In addition to theregular RFID response including the unique ID, the reflections of theincident signals are also used with a TDR analysis for determining otherinformation regarding the passive network and its elements.

The interrogator transceiver for sending signals may be located at afeed point of the passive DAS, such as a coverage port of a DAS remoteunit, and collects not only RFID information, but also reflected signalsto process, analyze, and make determinations of the layout(interconnectivity and location), and other information relevant for theoperation and maintenance of the passive DAS system.

FIG. 1 illustrates a block diagram depicting an embodiment of a DAS forincorporating various aspects of the invention. The DAS 10 can includeone or more master units 16 as a donor device that are coupled to one ormore remote units or remote antenna units 12 for coverage. The DAS 10can communicate with one or more base stations or other signal sources(not shown) via a wired or wireless communication medium as appropriate.The DAS and the master units 16 communicate uplink and downlink signalsbetween the base stations and one or more remote antenna units 12distributed in an environment, such as an indoor environment, to providecoverage within a service area of the DAS 10. The master units 16 canconvert downlink signals received from the base station or signalsource, such as RF signals, into one or more data streams fortransmission to the remote antenna units 12. The data streams consist ofthe representation of the RF communication signals and communicationdata between a system controller 22 and remote unit controller asdiscussed herein. The data streams might be digital or analog datastreams or may include both digital and analog data. The remote antennaunits 12 can convert digital data streams to RF signals. The remoteantenna units 12 can amplify the downlink signals and radiate thedownlink signals 24 to terminal equipment or customer equipment, such asone or more wireless communication devices 26. Uplink signals arehandled similarly in the uplink direction and are received from thedevices 26 by the remote antenna units 12 and converted from RF todigital data streams and transmitted to the master units 16 and beyond.

A system controller 22 can control the operation of the master units 16for processing the signals communicated with the remote antenna units12. The signals communicated with the remote antenna units 12 may be theuplink and downlink signals of the DAS 10 for communicating withterminal equipment. The master units 16 can provide downlink signals tothe remote antenna units 12 via the links 20. The links 20 can includeany communication medium suitable for communicating data signals betweenthe master unit 16 and the remote antenna units 12. The signals may becommunicated electrically or optically. Non-limiting examples of asuitable communication medium for the links 20 can include copper wire(such as a coaxial cable), optical fiber, and microwave or opticalcommunication links.

Although the DAS 10 is depicted as including a couple master units 16and remote antenna units 12 coupled to a master unit, any number(including one) of each of master unit 16 and remote antenna units 12can be used. Furthermore, a DAS 10, according to some aspects, can beimplemented without system controller 22.

FIG. 2 is a block diagram of an exemplary remote antenna unit 12configured for performing TDR measurements and correlating themeasurements with RFID data and information related to various passiveelements within the DAS network. The remote antenna units (RU) 12 may beincorporated with larger overall DAS through a suitable communicationmedium 18. Conversion circuitry 20 might be implemented, such as toconvert optical signals to electrical signals for transmission to one ormore antennas 34. The remote unit 12 may be coupled to the antenna 34through a suitable communication medium or waveguide, such as a coaxialcable 30. Appropriate connector elements of the cable 30 defineconnection junctures 36, 38 associated with the passive elements. Forexample, connection juncture 36 is associated with the passive elementof cable 30 that connects the remote unit 12 and another possiblepassive element of antenna 34, and indicates a location of one end ofthe cable. The connection juncture 38 is associated with the antenna 34,and the location thereof. For example, the cable 30 might be connectedto the coverage port of a remote unit 12 at one end to define juncture36. The other end of cable 30 connects with coverage antenna 34 todefine connection juncture 38. In accordance with one aspect of theinvention, RFID systems, such as tags, are associated with passiveelements and might be located in the cable connectors and/or the base ofthe antenna, or might be closely located at the junctures 36, 38 forproviding information identifying the cable 30 and antenna 34, or someother passive element. In that way, the DAS remote unit 12 might scanthe antenna network, and retrieve the information identifying passiveelements such as cable 30 and antenna 34 from received RFID data.Additionally, signal wave reflections associated with the variousconnection points or junctures 36, 38 might be utilized for measuringparameters of the various passive elements, as discussed herein.

In one embodiment, Time Domain Reflectometry (TDR) is used for measuringparameters of the passive elements. As illustrated in the figures, theRFID systems/tags 40 are coupled in the signal path and with the passiveelements using appropriate coupling circuits or devices 42. For sendingsignals for the TDR measurement, as well as for the interrogation of theRFID systems 40, suitable interrogation and transceiver circuitry, inthe form of an interrogator 52 may be implemented in the remote unit 12,and appropriately coupled through a coupling device 54 to the cable 30and other passive elements, such as antenna 34.

Each of the RFID systems 40 associated with a passive element at aconnection juncture can include a unique, non-removable, andtamper-proof serial number or other data to describe technicalcharacteristics of the passive element, similar to an RFID tag, and eachof the RFID systems 40 can allow the respective passive component to beidentified. The RFID interrogator/transceiver 52 might have suitableprocessing circuitry therein to handle the processing of TDR signals forparameter measurements and RFID data signal handling in accordance withthe invention. Alternatively, a system controller 50 that is incommunication with an RFID interrogator/transceiver 52 or otherreader/interrogator system in the remote antenna unit 12 might haveprocessing circuitry for handling processing tasks. The interrogationprocess can be initiated in a number of ways, such as by the systemcontroller 50 or interrogator 52, or by the master unit systemcontroller 22. One or more incident signals are generated and sent bythe interrogator 52 to measure and identify the passive DAS elements.The RFID interrogator 52 can transmit the incident signal(s) through anappropriate coupling device or circuit 54. The coupling device 54 can bea directional coupler or a non-directional coupler. In one example, thecoupling device 54 can have a coupling ratio of −10 dB or smaller withrespect to the coaxial cable 30 in the direction to the RFID systems andassociated passive elements. In other aspects, the RFID interrogator 52can transmit the signal(s) via a low pass, band pass, or high passfilter.

For coupling the RFID signals in accordance with the invention, variousappropriate coupling circuits or devices 42 might be used. For example,an RFID system 40 of a passive element might be coupled to anotherpassive component, such as a coaxial cable 30 or other waveguide, via aresonant coupling circuit 42 that includes an attenuation and matchingcircuit. One coupling circuit 42 might use a capacitor and an inductorarrangement to have a certain resonant characteristics. The resonancefrequency can be the operational frequency of the RFID system 40. Forfrequencies separate from the resonance frequency, the coupling circuit42 can provide a high impedance to minimize negative impacts fromsignals used for mobile communication via the DAS 10. Non-limitingexamples of negative impacts from signals used for mobile communicationcan include reflection and loss to other signals on differentfrequencies. An attenuation and matching circuit can include attenuationdevices. Other implementations are also possible. In other aspects, aBalun component, such as (but not limited to) a transformer, can be usedin place of the attenuation devices. In additional or alternativeaspects, the RFID system of the invention can be coupled to the coaxialcable 30 or another passive component via a non-resonant couplingcircuit, such as a directional coupler. The directional coupler can beused with a coupling optimized for signals communicated with the RFIDinterrogator 52 and selected for suppressing potential intermodulationproducts generated by the RFID system 40 in the direction of one or moreantennas.

For providing interrogation of the RFID systems 40 of the invention, aninterrogation signal from interrogator 52 can be communicated via thecoaxial cable 30. The interrogation signal can experience some loss dueto the nature of the coaxial cable 30 or other waveguide. One or more ofthe RFID systems 40 can receive an interrogation signal that has asignal level above a predetermined threshold for the RFID system.Non-limiting examples for such a threshold include signal levels between−15 dBm and −18 dBm. One or more of the RFID systems 40 can receive theincident interrogation signal via a respective one of the couplingcircuits 42. One or more of the RFID systems 40 can then generate aresponsive signal that contains RFID data. The responsive signal can becommunicated back to the RFID interrogator 52 via the coaxial cable orother waveguide.

In accordance with one aspect of the invention, interrogator 52 isconfigured for generating at least one incident signal for transmissionto a passive element to be reflected at a connection juncture associatedwith that passive element, and the location of that passive element inthe network. The reflected signal is processed for measuring a parameterof the passive element. In one embodiment, a TDR method is used in orderto measure reflections along the conductor, such as along cable 30, andat the connection juncture of the various passive elements. Assumingthat the conductor (e.g., cable 30) is of uniform impedance, the variousconnectors defining connection junctures, such as 36, 38 that defineconnection locations between the various network elements such as cable30 and antenna 34, will introduce impedance variations in thetransmissions mediums, such as cable 30. TDR, or Time DomainReflectometry, is a measurement technique that is used to determineparameters and characteristics of a passive element by observing thereflected signal waveforms associated therewith. For example, theimpedance parameters at a discontinuity, such as connection junctures36, 38, can be determined from the amplitude of the reflected signal.Also, a parameter, such as the distance to the reflecting impedance, canbe determined from the time that an incident measurement pulse wouldtake to return from a reflection point (36, 38) back to interrogator 52,for example. More specifically, at the point of the impedance variation,the incident signal will be reflected back toward the signal source,such as interrogator 52. The signal propagation delay is correlated withthe distance from that signal source. In that way, a parameter, such asthe length of the transmission medium, such as cable 30, is determinedby looking at the transmitted and the received interrogation signal orother signals for junctures 36, 38 in the time domain.

Referring to FIG. 2, various RFID systems/tags 40 may be located in thecable connectors at the remote unit output port (36), and at the base ofthe antenna 34 (38). One or more measurements/interrogation signals aresent by interrogator 52 so that the DAS remote unit 12 can scan thepassive network, and retrieve the information identifying the cable 30,as well as antenna 34. The RFID systems 40 associated with the variouspassive elements at the cable connector and the base of antenna 34respond to the interrogation signal to return RFID data to theinterrogator 52 for the proper identification of those passive elements.Processing circuitry in the interrogator and/or controller 50 receivesthe RFID data.

In accordance with another aspect of the invention, thatmeasurement/interrogation signal will also provide a reflectionassociated with each of the connection junctures 36, 38 associated withthe connection points or locations for the passive elements. Thatreflection information from a reflected signal is used by the processingcircuitry of interrogator 52 and/or controller 50, and is processedaccording to an appropriate TDR methodology, for example, to evaluate aparameter, such as the distance between the coverage port of the remoteunit 12 and antenna 34. Processing circuitry in the interrogator and/orcontroller 50 correlates the returned RFID data and the measureddistance parameter information from the TDR processing in order tocharacterize each of the passive elements in the network and theirdistance from the coverage port of the remote unit 12.

In addition to the distance information, the TDR processing may alsoprovide the magnitude of the impedance mismatch at the variousconnection junctures 36, 38. The impedance magnitude information may beused to identify any damaged passive network elements, and to also yieldinformation on the physical distance of those damaged elements from thesignal source, such as the interrogator 52 and the remote unit 12.

In accordance with another aspect of the invention, insertion loss ofthe passive network elements is measured. The insertion loss measurementmay be made in a number of ways. In one example, utilizing the TDRmethodology, by making the end of a cable produce a total reflection(such as by switching or connecting it to an open circuit termination orshort circuit termination), then the interrogator might determine theloss from comparing the power of the transmitted signal with thereceived signal. In another example, if the transmitted RFID power isknown, it can be compared with a measured received RFID power, and theloss between the transmitter and receiver can be calculated. With theknowledge of the cable insertion loss characteristics from the RFID dataand the received power at the used frequency, the cable insertion lossat other frequencies could also be estimated.

In accordance with one aspect of the invention, a single signal is usedfor RFID data and also for obtaining a reflected signal for measurementpurposes. For example, the TDR measurement signal may also act as aninterrogation signal for the RFID systems 40. The TDR signal is used asa trigger for the RFID system or chip 40 to send the RFID data inresponse. The reflection information provided at various connectionjunctures and impedance mismatches, and the measured parametersassociated therewith, may then be correlated with the RFID data so thatdistance measurements and other parameter measurements are correlatedwith a specific identified passive element. That is, the obtained RFIDdata and reflection may arrive at the interrogator 52 close enough intime to provide such a correlation through the passive circuitry.

In an alternative embodiment, as discussed herein, a separate signalmight be used to obtain RFID data, and another signal used, such as apulse signal, to obtain a reflected signal for measuring one or moreparameters of a passive element utilizing a TDR methodology or othermethodology.

FIG. 3 illustrates a more complex antenna network implementing theinvention. Specifically, multiple antennas 34 are coupled with theremote unit 12 through an appropriate passive RF splitter 32 and cables30. Various of the RFID systems 40 might be coupled at appropriateconnection junctures 36, 38 associated with the cables 30 that connectthe RF splitter to the remote unit, and the multiple antennas 34 to theRF splitter 32.

As noted herein, interrogator 52 and/or controller 50 will process thereflected TDR signals as well as the RFID data to characterize thepassive network and the elements therein. As may be appreciated, theprocessing circuitry of the interrogator/controller may have to processmultiple reflections and correlate the TDR information and measuredparameters associated with those reflections with specific RFID data toprovide information regarding the particular passive element orconnection point that is associated with the reflections and measuredparameters. The different propagation times associated with TDRreflections and the return of RFID data from the RFID systems 40 may beaddressed in accordance with one aspect of the invention. For example,for TDR methods, you often only need a short pulse signal that is sentand somewhat quickly reflected and returned. For gathering RFID data, onthe other hand, it may be necessary to send a longer signal in order totrigger the RFID system. Because of the different propagation aspects,the interrogator/controller might receive all of the TDR reflectionsbefore the RFID systems 40 have sent their information. As a result, theinterrogator/controller is configured with appropriate logic to matchthe TDR reflection information and other measurements to specific RFIDdata that identifies the passive elements that are associated withmeasured parameters.

To assist in that processing, in accordance with one aspect of theinvention, other interrogators might be implemented that operate as“slave” interrogators with interrogator 52 in the remote unit operatingas a “master” interrogator. To that end, as illustrated in FIG. 3, aslave interrogator (SI) 41 might be incorporated, for example, into theRF splitter 32 that connects with multiple antennas 34. In oneembodiment as illustrated, the slave interrogation functionality mightbe incorporated within the processing circuitry of the RFID system sothat element 41 provides functionality both as an RFID system thatprovides RFID data, as well as an interrogator. Because of its locationin a passive element such as an RF splitter, the slave interrogator 41may not have a power source. In one embodiment, the slave interrogator41 is charged by interrogator 52, which is considered the masterinterrogator. For example, one or more signals may be sent from masterinterrogator 52 to slave interrogator 41 in order to charge and powerthe slave interrogator 41. Then, the slave interrogator 41 sends theRFID interrogation signal and/or TDR pulse signals to the passiveelements, such as cable 30, and the various antennas 34. The returnedRFID data and/or reflected TDR pulses are then returned back to themaster interrogator 52, where they are processed for measuring certainparameters and correlated to provide information regarding the differentpassive elements, in accordance with the invention.

In an alternative embodiment of the invention, the slave interrogator 41will be similarly energized by the master interrogator 52 and signalstherefrom. However, the slave interrogator 41 is also configured withappropriate processing circuitry to process RFID data and/or TDR pulsedata. The slave interrogator sends interrogation signals/TDR pulses in asingle branch or path from the RF splitter 32, such as to a specificantenna 34. The slave interrogator 41 then receives the TDR reflectionand/or any RFID data associated with the passive elements in thatbranch. The slave interrogator 41 can then proceed to the next branchsequentially, until all of the various antenna elements 34 and orderpassive elements have been addressed. The slave interrogator 41 thenprocesses the RFID information, and parameter measurement informationresulting from TDR processing, and sends that information back to themaster interrogator 52.

As noted herein, a single pulse or signal might be sent by aninterrogator to act as both an RFID interrogation signal, as well as theTDR pulse. The returned RFID data is then correlated with the specificTDR reflection so that TDR parameter measurement information may beassociated with a specific passive element in the DAS network.

Alternatively, different signals might be sent to affect the RFIDfeatures of the RFID systems 40, 41 separate from the TDR measurements.For example, one or more RFID interrogation signals may be sent toenergize a particular RFID system 40, 41 so that it can prepare asuitable response to return the RFID data associated with that systemand with the particular passive network element. Then, the interrogatorsends a TDR pulse signal, which acts as a trigger for the RFID system.The TDR pulse is reflected, and a received reflected signal is processedand used for the noted TDR measurements. The triggered RFID system alsoreturns RFID data to the interrogator. In that regard, the RFID dataresponse from the RFID system 40, 41 may be somewhat closer in time tothe returned TDR reflection. Depending on how many elements are to beinterrogated and measured, stronger RFID signals or multiple RFIDsignals might be utilized to charge the various systems 40, 41 beforethey are triggered with a TDR pulse.

In accordance with another aspect of the invention, to assist inprocessing the TDR information and RFID data associated with varioussignal paths and various passive network elements, the RFID systems 40,41 might be selectively controlled to be turned ON and OFF, as desired,for making specific measurements. In that way, the processing circuitry,whether associated with the interrogator 52 or controller 50 or a slaveinterrogator 41, might be able to control which passive elements aresending RFID data that is correlated with reflections so as to moreaccurately characterize the system.

While the disclose embodiments illustrated utilization of the inventionon the covered side of a distributed antenna system, such as at thevarious remote unit 12, the present invention might also be used toidentify and characterize the passive network on the donor side, such asbetween the distributed antenna system, and the feeding base transceiverstations (BTS), or other signal sources. Therefore, the presentinvention is utilized in characterizing various passive networks,regardless of their location within a distributed antenna system.

While the present invention has been illustrated by the description ofthe embodiments thereof, and while the embodiments have been describedin considerable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details representative apparatusand method, and illustrative examples shown and described. Accordingly,departures may be made from such details without departure from thespirit or scope of applicant's general inventive concept.

Example Embodiments

Example 1 includes a distributed antenna system comprising: a pluralityof remote antenna units, a first passive element coupled to at least oneof the remote antenna units at a connection juncture; an RFID systemassociated with the first passive element and having RFID dataidentifying the first passive element; an interrogator unit associatedwith the remote antenna unit, the interrogator unit configured forgenerating a least one signal for transmission to the passive element tobe reflected at the connection juncture and received at the interrogatorunit; the interrogator unit configured for generating at least onesignal for transmission to the RFID system to obtain the RFID dataidentifying the passive element; processing circuitry for processing thereflected signal and for measuring a parameter of the first passiveelement, the processing circuitry further configured for correlating themeasured parameter with the RFID data for the passive element.

Example 2 includes the distributed antenna system of Example 1 whereinthe processing circuitry is configured for processing the reflectedsignal using a time domain reflectometry method.

Example 3 includes any of the distributed antenna systems of Examples1-2, wherein the at least one signal of the interrogator that is to bereflected and the at least one signal of the interrogator to obtain theRFID data are the same signal.

Example 4 includes any of the distributed antenna systems of Examples1-3 wherein the at least one signal of the interrogator that is to bereflected and the at least one signal of the interrogator to obtain theRFID data are different signals.

Example 5 includes any of the distributed antenna systems of Examples1-4 wherein the interrogator is part of the remote antenna unit.

Example 6 includes any of the distributed antenna systems of Examples1-5 further comprising a second passive element coupled with the firstpassive element at a connection juncture and an RFID system associatedwith the second passive element and having RFID data identifying thesecond passive element.

Example 7 includes the distributed antenna system of Example 6 furthercomprising a second interrogator unit associated with the first passiveelement and configured for generating at least one signal fortransmission to the second passive element to be reflected at the secondpassive element connection juncture.

Example 8 includes the distributed antenna system of Example 7 whereinthe first interrogator unit is configured for receiving the signalreflected at the second passive element connection juncture, theprocessing circuitry processing the reflected signal for measuring aparameter of the second passive element.

Example 9 includes the distributed antenna system of Example 8, thesecond interrogator unit is configured for generating at least onesignal for transmission to the RFID system of the second passive elementto obtain the RFID data identifying the second passive element, theprocessing circuitry further configured for correlating the measuredparameter of the second passive element with the RFID data for thesecond passive element.

Example 10 includes a method of characterizing a first passive elementof a distributed antenna system that comprises a plurality of remoteantenna units, the first passive element coupled to at least one of theremote antenna units at a connection juncture, the method comprising:generating, by an interrogator unit associated with the remote antennaunit, at least one signal for transmission to the passive element to bereflected at the connection juncture and received at the interrogatorunit; generating, by the interrogator unit, at least one signal fortransmission to an RFID system associated with the first passiveelement, to obtain RFID data identifying the first passive element;processing the reflected signal and measuring a parameter of the firstpassive element; and correlating the measured parameter with the RFIDdata for the passive element.

Example 11 includes the method of Example 10 further comprisingprocessing the reflected signal using a time domain reflectometrymethod.

Example 12 includes any of the methods of Examples 10-11 wherein the atleast one signal of the interrogator that is to be reflected and the atleast one signal of the interrogator to obtain the RFID data are thesame signal.

Example 13 includes any of the methods of Examples 10-12 wherein the atleast one signal of the interrogator that is to be reflected and the atleast one signal of the interrogator to obtain the RFID data aredifferent signals.

Example 14 includes any of the methods of Examples 10-13 wherein theinterrogator is part of the remote antenna unit.

Example 15 includes any of the methods of Examples 10-14 wherein asecond passive element is coupled with the first passive element at aconnection juncture, and a second RFID system is associated with thesecond passive element and having RFID data identifying the secondpassive element.

Example 16 includes the method of Example 15 further comprisinggenerating at least one signal for transmission to the second passiveelement to be reflected at the second passive element connectionjuncture.

Example 17 includes the method of Example 16, wherein the at least onesignal for transmission to the second passive element is generated by asecond interrogator unit associated with the first passive element.

Example 18 includes the method of Example 17 further comprising:receiving, by the first interrogator unit, the signal reflected at thesecond passive element connection juncture; and processing the reflectedsignal for measuring a parameter of the second passive element.

Example 19 includes the method of Example 18 further comprising:generating, by the second interrogator unit, at least one signal fortransmission to the RFID system of the second passive element to obtainthe RFID data identifying the second passive element; and correlatingthe measured parameter of the second passive element with the RFID datafor the second passive element.

What is claimed is:
 1. A distributed antenna system comprising: aplurality of remote antenna units, a first passive element coupled to atleast one of the remote antenna units at a connection juncture; and anRFID system associated with the first passive element and having RFIDdata identifying the first passive element; wherein the system isconfigured so that at least one signal transmitted to the first passiveelement is reflected at the connection juncture; wherein the system isconfigured so that at least one signal transmitted to the RFID system isused to obtain the RFID data identifying the first passive element; andwherein the system further comprises processing circuitry configured toprocess the reflected signal and to measure a parameter of the firstpassive element.
 2. The distributed antenna system of claim 1, whereinthe processing circuitry is configured to process the reflected signalusing a time domain reflectometry method.
 3. The distributed antennasystem of claim 1, wherein the at least one signal that is reflected andthe at least one signal that is used to obtain the RFID data are one of:the same signal and different signals.
 4. The distributed antenna systemof claim 1, wherein the processing circuitry is further configured tocorrelate the measured parameter with the RFID data for the passiveelement.
 5. The distributed antenna system of claim 1, furthercomprising an interrogator configured to transmit the at least onesignal that is reflected.
 6. The distributed antenna system of claim 5,wherein the interrogator is part of the remote antenna unit.
 7. Thedistributed antenna system of claim 1, further comprising a secondpassive element coupled with the first passive element at a connectionjuncture and a second RFID system associated with the second passiveelement and having second RFID data identifying the second passiveelement.
 8. The distributed antenna system of claim 7, wherein thesystem is configured so that at least one signal transmitted to thesecond passive element is reflected at the second passive elementconnection juncture.
 9. The distributed antenna system of claim 8,wherein the processing circuitry is configured to process the reflectedsignal reflected at the second passive element connection juncture inorder to measure a parameter of the second passive element.
 10. Thedistributed antenna system of claim 9, wherein the system is configuredso that at least one signal transmitted to the second RFID system of thesecond passive element is used to obtain the second RFID dataidentifying the second passive element.
 11. A method of characterizing afirst passive element of a distributed antenna system that comprises aplurality of remote antenna units, the first passive element coupled toat least one of the remote antenna units at a connection juncture, themethod comprising: transmitting at least one signal to the first passiveelement in order to be reflected at the connection juncture;transmitting at least one signal to an RFID system associated with thefirst passive element in order to obtain RFID data identifying the firstpassive element; and processing the reflected signal and measuring aparameter of the first passive element.
 12. The method of claim 11,further comprising processing the reflected signal using a time domainreflectometry method.
 13. The method of claim 11, wherein the at leastone signal that is reflected and the at least one signal that is used toobtain the RFID data are one of: the same signal and different signals.14. The method of claim 11, further comprising: correlating the measuredparameter with the RFID data for the passive element.
 15. The method ofclaim 11, wherein transmitting the at least one signal to the firstpassive element in order to be reflected at the connection juncturecomprises: transmitting the at least one signal from an interrogator tothe first passive element in order to be reflected at the connectionjuncture.
 16. The method of claim 15, wherein the interrogator is partof at least one remote antenna unit.
 17. The method of claim 11, whereina second passive element is coupled with the first passive element at aconnection juncture and a second RFID system associated with the secondpassive element and having second RFID data identifying the secondpassive element.
 18. The method of claim 17, further comprising:transmitting at least one signal to the second passive element in orderto be reflected at the second passive element connection juncture. 19.The method of claim 18, further comprising: processing the reflectedsignal reflected at the second passive element connection juncture inorder to measure a parameter of the second passive element.
 20. Themethod of claim 19, further comprising: transmitting at least one signalto the second RFID system of the second passive element in order toobtain the second RFID data identifying the second passive element.